1. Field of the Invention
The present invention relates to a data conversion apparatus and a recording apparatus that perform horizontal-to-vertical conversion on the arrangement of image data.
2. Description of the Related Art
Some conventional recording apparatuses employ an ink jet recording method in which ink is ejected for image formation. In this recording method, a recording head having a plurality of nozzles with a predetermined width along which a recording medium is fed is used. For carrying out the recording operation, this recording head, in general, performs scanning perpendicularly to the arrangement of the nozzles (hereinafter referred to as "the main-scanning direction), while a recording medium is fed perpendicularly to the main-scanning direction (hereinafter referred to as "the sub-scanning direction).
The resolution of the image data received by a facsimile machine having a built-in recording apparatus of the above type from other types of facsimile machines is determined to be 8 pel/mm in the main-scanning direction and 7.7 line/mm in the sub-scanning direction in compliance with, for example, the G3 fine mode. The arrangement of received image data is sometimes required to be converted prior to printing, depending on the arrangement of recording elements of the recording head (such converting processing will hereinafter be referred to as "the horizontal-to-vertical conversion" or simply referred to as "H-V conversion). Distortion would occur to the H-V converted image data output from the recording apparatus if no additional processing is executed, since the resolution of the recording apparatus usually differs from the resolution of facsimile images. For avoiding this problem, prior to the H-V conversion the resolution of the received image data in the main-scanning and sub-scanning directions is converted to the resolution which would be obtained after H-V conversion is performed.
The above-described resolution conversion and H-V conversion are performed in the following procedure. The image data in the main-scanning direction is converted in a resolution converting section built into a facsimile machine. The resulting image data is then stored in a zone of a storage medium, such as a RAM or the like. On the other hand, for enhancing the resolution of the image data in the sub-scanning direction, the data is copied line by line in another storage zone to create additional image data (data copying by a unit of line will hereinafter be referred to as "line copying" which will be described in greater detail below). Thereafter, H-V conversion is executed on the image data whose resolution is converted both in the main-scanning and sub-scanning directions.
However, the conventional facsimile machine of the above type encounters the following problems. The above-described resolution conversion and H-V conversion lengthen the time required for receiving the image data and outputting it from the recording apparatus, which decreases the total throughput of the facsimile machine. Also, memory having a large capacity is required for performing resolution conversion, which increase the size of the apparatus and costs.